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Medical/biological study (experimental study)

Anxiogenic effect of chronic exposure to extremely low frequency magnetic field in adult rats.

Published in: Neurosci Lett 2008; 434 (1): 12-17

Aim of study (acc. to author)

This study was performed to investigate whether the anxiety behavior of rats could be affected by repeated extremely low frequency magnetic field exposure of different daily durations.
Background/further details: Thirty male rats were used. Behavioral changes were examined in the morning of the 21th, 23th, and 25th exposure day.
Rats anxiety-related behaviors were examined in the open field test, elevated plus maze, and the light/dark box during five minutes observations. The open field was a black circular area (diameter: 160 cm, height: 50 cm) with two concentric circles lines on the floor. The elevated plus maze consisted of two opposite open arms, an open platform in the center, and two opposite closed arms. To avoid fear rats tend to stay close to the sidewall in the open field and to the closed arms in the elevated plus maze. Grooming is interpreted as a stress coping and de-arousal behavior response to increased anxiety level due to novel environment situations in the tests. The light/dark box was constructed from two equally sized boxes which were connected by an opening. In the dark box, there was no appreciable illumination. The light box was white and provided illumination at a level of 100 lux.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: 1 h/day or 4 h/day for 25 days
General information
animals were treated in three groups: i) no exposure ii) exposure for 1 h/day iii) exposure for 4 h/day
Exposure 1
Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration 1 h/day or 4 h/day for 25 days
Exposure setup
Exposure source
Setup pair of Helmholtz coils with a diameter of 80 cm, 40 cm apart; rats placed in the center of the coils system
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 2 mT - - - -
Exposed system:

Methods Endpoint/measurement parameters/methodology

  • cognitive/behavioral endpoints: Anxiety-related behaviors (open field test: recording of traveled distance, time spent in outer and inner ring, grooming, defecation, rearing; elevated plus maze: spent time/number of entries in the open/closed arm, time spent in the central part, rearing in the open arms; light/dark box: recording of time spent in the light box, transitions between two boxes, latency to the dark box, rearing in the light box)
Investigated material:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The magnetic field exposure for 4 hours/day increased the anxiety-like behaviors in rats in the open field test and the elevated plus maze test (increased time spent in outer ring than in central ring, increased grooming; reduced time spent in open arms and central part and increased time spent in closed arms). No effect was observed in the light/dark box test. Moreover, magnetic field exposure for 1hour/day had no effect in any test.
These findings suggest that the exposure to chronic extremely low frequency magnetic field has anxiogenic effect in rats, which is dependent on the daily exposure duration and which is more sensitive to void space than to strong light.
Study character:

Study funded by

  • not stated/no funding

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